The present invention relates generally to packaging for photographic film. In particular, the present invention is a resealable cassette or cartridge for medical imaging film.
X-ray and other types of medical imaging photographic film are typically packaged in optically opaque (i.e., light-tight) and photo-inert containers such as cassettes, magazines, cartridges and bags. The Wilcox U.S. Pat. No. 330,182, the Jones et al. U.S. Pat. No. 1,536,345 and the 1958 U.S. Naval Medical School publication entitled "Fundamentals of X-ray Physics & Technique" disclose a variety of containers for film storage and transportation. Medical imaging film commercially available from the 3M Company of St. Paul, Minn., the assignee of the present invention, is packaged in a flexible bag including layers of biaxially oriented polypropylene, aluminum foil and low density polyethylene which are laminated together by polyethylene bonding layers. The film must be removed from these packages and loaded into the x-ray machine, camera or other imaging device under darkroom conditions, an inconvenient procedure.
The Schmuck U.S. Pat. No. 1,098,844 discloses a film package which can be loaded directly into a camera, thereby alleviating the need for a darkroom. However, the Schmuck film package is relatively inefficient in design and requires manual manipulation to bring the film into exposure position. The Schmuck package is therefore incompatible with the automatic film handling mechanisms of modern imaging systems.
The Tajima et al. U.S. Pat. No. 4,727,391 discloses a package for sheet film and a loading device for the package. The package includes a tray and a flexible cover peelably attached to the tray by an adhesive. After the package is loaded into a loading device of an image recorder, the cover is peeled off, enabling a delivery mechanism to access the film. The adhesive layer has an edge portion inclined to the longitudinal direction of the tray so the cover can be peeled off easily.
Packages of the type shown in the Tajima et al. Patent typically contain many sheets of one specific type of film. However, depending on the nature of the image being exposed, it is often necessary to load different sizes and/or types of film into the imager. Any unexposed film remaining within a cartridge is therefore wasted if the cartridge must be removed from the imager so a new cartridge bearing a different type or size of film can be inserted.
International application Number PCT/EP88/00166 discloses an automatic film-loading device for sheet film cassettes. After a cassette is inserted into an unloading and reloading station in the device, the cassette is opened and the exposed sheet of film is seized, removed and transported to a developing apparatus. The cassette is then reloaded with a sheet of film from one of a plurality of supply magazines, each containing different sizes of film. The freshly loaded cartridge is then dispensed from the device for subsequent use. Although this automatic film-loading device reduces the waste associated with the removal of unused film from an imager, it is a complicated and relatively expensive accessory for the imager.
It is evident that there is a continuing need for improved film handling systems for photographic imagers. In particular, there is a need for a device which conveniently enables different sizes and/or types of film to be inserted into and removed from a medical imager without resulting waste. The device must be relatively inexpensive to be commercially viable.